How do I offset the start of a cloth simulation?
Workflow:


Bake the the cloth simulation by clicking Bake button in Cloth Cache panel.
Find a folder called blendchache_[project_file_name] in the same directory of the .blend project file.
Per-frame data were saved here as files named like [some_num]_000001_00.bphys, [some_num]_000002_00.bphys... etc, the mid-section was actually the frame number, e.g. 000001 means frame 1. Now you can simply delete files from 000001 to 000099.
Then you can rename the rest files to [some_num]_000001_00.bphys, [some_num]_000002_00.bphys, etc. (There are many free and handy file rename tools online for download, to do the renaming work in a flash)


You needn't close the project during the process. You can play the offset simulation right after that.

Tip:

This trick can be used to offset other simulation types that generate cached data.